For lithium-ion battery-based HEVs and PHEVs to become commercially viable, occurrences of rare but violent spontaneous field failures of lithium-ion cells must be prevented. We are developing a methodology to reliably and reproducibly implant and activate internal short circuits of the type believed to be responsible for field failure incidents in lithium-ion cells. This methodology is being used to develop battery safety technologies for mitigating safety incidents of internal short circuits in lithium-ion cells. Commercial Applications and Other Benefits: Safer lithium-ion batteries will be of benefit to existing portable power applications (e.g. laptops, cell phones, power tools), while at the same time enabling the implementation of Li-ion technology in the emerging HEV and PHEV applications. HEVs and PHEVs will have substantial positive impact on national energy efficiency and energy independence.